Push-pull non-complementary transistor amplifier

Abstract

A push-pull amplifier having like conductivity output transistors is driven by a phase-splitter transistor amplifier. The collector load of the phase-splitter includes a diode bridge for establishing the amplifier idling current. One arm of the bridge incorporates the pull-up output transistor base-emitter junction-the current conducted therein being accurately determined by bridge parameters.

What is claimed is: 
     
       1. A push pull amplifier comprising: first and second terminals for supplying relatively positive and relatively negative supply potential respectively;   first and second current sources for supplying and sinking substantially equal currents;   first, second and third transistors of like conductivity type each having respective first and second electrodes, a principal conduction path therebetween, and having respective control electrode and wherein said principal conduction paths are controlled by respective potentials applied across their respective first and control electrodes;   a bridge circuit including first and second parallel connected arms, a first arm of which includes a plurality N of serially connected diode means and a second arm of which includes a series connection of the control and first electrodes of said second transistor and at least one diode means, the total number of series connected elements in the second bridge arm totaling N and wherein said at least one diode means is connected between the first electrode of the second transistor and the first bridge arm;   means serially connecting the first and second current sources, the bridge circuit and the principal conduction path of the first transistor between said first and second terminals with the first and second current sources most near to the first and second terminals respectively;   a current mirror amplifier having an input electrode connected to the first terminal of the first transistor and having an output terminal connected to the interconnection of the first electrode of said second transistor and said at least one diode means, said current mirror including said third transistor with its principal conduction path serially connected with the current mirror output terminal for determining its output current and wherein output signal is available from said push-pull amplifier from the first electrode of said second transistor.   
     
     
       2. The push-pull amplifier set forth in claim 1 wherein the bridge circuit comprises: a first bridge arm having two serially connected diode means; and   a second bridge arm including the series connection of the control and first electrodes of said second transistor and one diode means and wherein said control electrode of the second transistor is connected to one end of the first bridge arm and said one diode means is connected between the first electrode of said second transistor and the other end of said first bridge arm.   
     
     
       3. The push-pull amplifier set forth in claim 1 wherein the bridge circuit comprises: a first bridge arm having three serially connected diode means;   a second bridge arm including a fourth transistor having first, second and control electrodes, the control and first electrodes of said fourth transistor being connected between a first end of said second arm and the control electrode of said second transistor, the first electrode of said second transistor being connected to a first end of said at least one diode means, a second end thereof being connected to a second end of said bridge arm.   
     
     
       4. The push-pull amplifier set forth in claim 1, 2 or 3 wherein each of said diode means comprises a transistor having respective control and second electrodes interconnected to form a first diode terminal and said transistor first electrode forming a second diode terminal. 
     
     
       5. The push-pull amplifier set forth in claim 1, 2 or 3 wherein the current mirror amplifier comprises: said third transistor having its control, second and first electrodes respectively connected to the current mirror amplifier input, output and common terminals; and   further diode means connected between the current mirror amplifier input and common terminals and poled to conduct in a direction parallel with the principal conduction path of the third transistor.   
     
     
       6. The push-pull amplifier set forth in claim 5 wherein said first, second and third transistors are npn type bipolar transistors. 
     
     
       7. A push-pull amplifier comprising: first and second transistors of a like conducitivity type, and a third transistor, each transistor having first, second and control electrodes and having a principal conduction path between its first and second electrodes controlled by a potential between its control and first electrode;   
     
     
       first and second current sources; a bridge circuit including a like number greater than one of current dependent potential offset means in each of two arms, the bridge arms terminating in first and second common ends, one of said arms serially including the control and first electrodes of said first transistor with the first electrode of said first transistor remote from said first and second common ends;   means for serially connecting the first current source, the bridge circuit the second and first electrodes of the third transistor and the second current source in the recited order;   means for connecting the control and second electrodes of the second transistor to the respective first electrodes of the third and first transistors respectively; and   means for connecting the control and first electrodes of the second transistor across said second current source.   
     
     
       8. The amplifier set forth in claim 7 further including means connected between the control and first electrodes of the second transistor to configure the second transistor therewith as the output transistor of a current mirror amplifier. 
     
     
       9. The amplifier set forth in claim 8 wherein the current dependent potential offset means are unidirectional current conducting devices. 
     
     
       10. The amplifier set forth in claim 9 wherein the unidirectional current conduction devices comprise pn semiconductor junctions. 
     
     
       11. The amplifier set forth in claim 8, 9 or 10 wherein the means connected between the control and first electrodes of the second transistor to configure the second transistor therewith as the output transistor of a current mirror amplifier is a further transistor similar to said second transistor, said further transistor having its control and second electrodes connected to the control electrode of the second transistor and having its first electrode connected to the first electrode of the second transistor. 
     
     
       12. The amplifier set forth in claims 7, 8, 9 or 10 wherein the bridge circuit includes two forward biased diode means in a first of said two arms and a forward biased diode means serially connected with the first electrode of the first transistor in a second of said two arms and wherein output signal from the amplifier is available at the first electrode of said first transistor. 
     
     
       13. A push-pull amplifier comprising: first and second bipolar transistors of a first conductivity type and a bipolar driver transistor, each having collector, base and emitter electrodes;   first and second constant current sources for sourcing and sinking equal currents, said first and second current sources connected as collector and emitter loads respectively for said driver transistor;   a bridge circuit connected between the first current source and the driver transistor collector electrode, said bridge circuit having a plurality N of pn junctions in a first arm thereof and a plurality N of pn junctions in a second arm thereof one of which being the base-emitter junction of the first transistor, there being at least one pn junction in said second arm interposed between the emitter electrode of the first transistor and the collector electrode of the driver transistor;   means for connecting the collector and base electrodes of the second transistor to the emitter electrodes of the first and driver transistors respectively;   potential supply means connected for conditioning the first and second transistors for normal operation; and   wherein input signal potential is applied to the base electrode of the driver transistor and output signal is available at the emitter electrode of the first transistor.